The present invention relates to estimating the focus position of a camera lens within an electronic device.
Many electronic devices include cameras with focus capabilities. An electronic device including a camera may include manual focus, auto-focus, or both. Exemplary electronic devices include, but are not limited to, mobile telephones, personal digital assistants, portable music players, portable video players, and portable computer systems such as laptops, notebooks and tablet computers. During a manual focus or auto-focus operation, a lens driver in the camera adjusts the focus position of the camera lens, which is the distance between the center of the camera lens and the sensor imaging plane. The focus position of a camera lens may be used by applications, such as within imaging or computer vision applications. The focus position can be used within these applications to determine geometric information, such as the distance of an object from the camera, for example.
During a focus operation, the focus position of the camera lens is adjusted using a lens driver, which is powered using a drive current. The value of the drive current can be used to estimate the focus position. However, estimating the focus position based solely upon a measured drive current can lead to inaccurate results due to variables, such as the orientation of the electronic device. Thus, a need exists for an improved technique of accurately estimating a focus position for a camera lens.